This invention relates to a device for the cleaning of a liquor spray nozzle assembly of a soda recovery boiler of the type that includes a liquor supply conduit inserted through an opening in a wall of the soda recovery boiler, which conduit has a mouth from which a plate for the distribution of liquor protrudes, more precisely from a lower part of the mouth.
In modern pulp mills, the major part of the cooking chemicals are recovered. After washing the pulp, the obtained waste liquor is evaporated, and then this is used as a fuel in a suitable boiler. Sulphate waste liquor (so called black liquor), and in certain case sulphite waste liquor, is burnt in a soda recovery boiler in a reducing atmosphere at approx. 1000xc2x0 C. For this purpose, liquor spray nozzles of the above generally mentioned kind are used. It is important that these liquor spray nozzles give an even distribution of the injected liquor in that an uneven distribution causes a risk that the bed at the bottom of the soda recovery boiler blackens with inferior degrees of reduction and deteriorated combustion emissions as a consequence.
A problem with the liquor spray nozzles is that the liquor gets burnt and stuck adjacent to the mouth of the spray nozzles and the distributing plate connected thereto. Above all, the material sticks on the side edges and undersides of the distributing plate while forming successively growing crusts with a sticky to hard consistency. The material crusts which stick in the angular transition section between the mouth of the liquor spray nozzle assembly and the horizontal distributing plate are specially cumbersome by the fact that such crusts obstruct a distribution of the liquor laterally from the distributing plate.
In order to overcome the crust formation phenomenon, inevitable per se, manual poking or hacking has previously been resorted to. In more difficult cases, the liquor spray nozzle assembly has to be dismounted from the wall opening of the soda recovery boiler and be cleaned separately. Both these alternatives are cumbersome and laborious. Furthermore, they have a detrimental impact on the combustion process.
The present invention aims at providing a cleaning device which can fulfil the purpose thereof without manual work of poking and without the need to dismount the liquor spray nozzle assembly. Thus, a primary object of the invention is to provide a cleaning device which with regular intervals makes sure that inevitable liquor material crusts are removed from the mouth and distributing plate of the liquor spray nozzle assembly without having to interrupt the operation of the liquor spray nozzle assembly. Another object is to provide a device which is simple and cheap to manufacture construction-wise. Furthermore, the device should be able to work also if the liquor spray nozzle assembly is adjusted in different angle positions in relation to the wall of the soda recovery boiler.
According to the invention, at least the primary object is attained by the features defined in the characterizing clause of claim 1. Preferred embodiments of the invention are furthermore defined in the dependent claims.